Box structures



May 17, 1960 Filed Oct. 19, 1956 O. LUNDQUIST BOX STRUCTURES 4 Sheets-Sheet 1 mmvroa 0104s? Lu/voou/Jr ATTORNEY May17, 1960 o. LUNDQQUIST 2,936,939

BOXSTRUCTURES Filed Oct. 19, 1956 4 Sheets- Sheet 2 INVENTOR Ourse (way/Jr ATTORNEX y 1960 o. LUNDQUIST 2,936,939

BOX STRUCTURES Filed Oct. 19, 1956 4 Sheets-Sheet 3 Ifnua. 11]] mmvrox. 0414/5? lu/v aa/sr y 1960 o. LUNDQUIST 2,936,939

BOX STRUCTURES Filed Oct. 19, 1956 4 Sheets-Sheet 4 INVENTOR. 010 5? Zwvo (pa/s 7- ]IHIEJQEB 2 4 ATTOAA/ X United States PatefitO 2,936,939 Box STRUCTURES Oliver Lundquist, Westport, Conn. Application October 19,1956, Serial No. 617,068

Claims. (Cl. 229-8) This invention relates generally to box structures, and more particularly is directed to ornamental box structures of cardboard, stilf paper, plastics or other suitably rigid sheet material.

It is an object of the present invention to provide octahedral box structures, that is, box structures having eight plane triangular faces.

Another object is to provide octahedral box structures which can be stored or shipped in flat condition, and then easily erected. I

Another object is to provide an octahedral, collapsible box structure which is openable along two contiguous edgesv lying in the same plane when the box is erected,

and which has simple means at said edges forclosing the latter and maintaining the collapsible box structure in its erected condition. 1 g

Still another object is to provide one-piece blanks of stiff paper, cardboard or the like, which can be folded and glued to form octahedral box structures.

7 A further object is to provide blanks of the described" character which can be cut, in nested relation, from a web or length of stifi paper, cardboard or'other suitably rigid sheet material, to reduce to the minimum the wasted' portions of the sheet material.

board or the like structure having two superposed, co-

extensive layers each including a series of four triangular portions having successive common sides along which the triangular portions of each'layer are hingedly connected, with such common sides all converging to a single point, the edges of the two layers being hingedly conneeted'to' each other only along the sides of the respective triangular portions which are remote from the single point where the related common sides converge, so that, when, the two layers move laterally apart at said single points thereof, the flat structure attains the erected form of a hollow octahedron with the free edgepo'rtions of the two layers then defining an opening along two contiguous edges of the octahedron lying in the samejplane.

described flat structure has hinged flaps extending alon'g the free edge portions. of theltwolayers at the sides of the opposite end triangular portions of the series 'of the latter making up the two layers, such flaps being adapted to extend across the opening of'the erected octahedral present invention;

ice Y 2 in two groups of equal number, the four triangular portions of each group having successive common sides all converging to a single point, and one triangular portion of one of said groups having a single common side with one triangular portion'of the other group.

The above, and other objects, features and advantages of the present invention, will be apparent in the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying draiwngs forming a part hereof and wherein:

Fig. 1 is a plan view showing one-piece blanks cut from a stripor web of sheet material in accordance with one embodiment of the invention;

Fig. 2 is a plan view of a fiat structure formed from a blank of the kind shown in Fig. 1;

Fig. 3 illustrates the appearance of the structure of Fig. 2 following the partial erection thereof;

' Fig. 4 is a perspective view of an octahedral box resulting'from the full erection of the flat structure of Fig. 2;

Fig. 5 is a side elevational view of the octahedral box of Fig. 4;

a Fig. 6 is a top plan view of the octahedral box of Figs. 4 and 5;

Fig. 7 is aview similar to Fig. 1, but illustrating other one-piece blanks from which the flat structure and box of Figs. 2 and 4, respectively, may be formed;

Fig. 8. is a plan view of another blank embodying the Fig. 9 is a view similar to that of Fig. 5, but showing a box formed from the blank of Fig. 8;

' Fig. 10 is a plan view of still another blank embodying the present invention;

Fig. ll is a view similar to Figs. 5 and 9, but showing abox formed from the blank of Fig. 10; and

Fig. 12 is a fragmentary, enlarged topplan view illustrating the details of a feature of octahedralboxes embodying this invention. 1

Referring to thedrawings in detail, and initially to Figs. 3,4,5 and 6, it will be seen that a box structure embodying the present invention and there generally identified by the reference numeral 10 includes eight triangular plane faces 11, 12, 13, 14,15, 16, 17 and 18 which define an octahedron. The face 11 has common sides with the faces 14 and 15 to define edges 19 and 20, respectively, of the box 10. The face 12 has common sides with the faces 13 and 16 to define edges 21 and 22, re

spectively, of the box. The face 15 has common sides with the faces 16 and 18 to define edges 23 and 24, re.-.

spectively, of the box. The face 17'has common sides with the faces 13, 16 and 18 to define edges 25, 26 and 27, respectively, of the box (Fig. 5), while the face 18 has a common side with the face 14 to define an edge 28 of the box. The faces of the box 10 having'common sides along the edges 19 to 28, inclusive, are there hingedly connected to each other, while the adjacent sides of the faces 11 and 12 defining an edge 29 (Figs. 4 and 6) and Further, in accordance with this invention, th'e'above the'adjacent sides of the faces 13 and 14 defining an edge 30 .(Fig. 6) are free of each other so that the box 10 is openable along the two contiguous edges 29 and 30 which lie in the same plane when the box is closed or fully erected, as is apparent from Fig. 6.

box and to interlock at their adjacent ends for closing the H opening and holding the box in its erected condition.

In accordance with still another aspect of this invention, a one-piece blank is used to form the above described that structure and'the octahedral box erected therefrom,f said blank including eight triangular'portions arranged In order to open the box 10, is only necessary to press toward eachother the apices 31 and 32 thereof at the junction of the edges,20,.22 and 23 and at the junction of the'edges 25, 27 and 28, respectively, thereby to angu larly spread open the adjacent free sides of the faces 11 and 12 and of the faces 13 and 14, respectively. In order to close the box 10, it is only necessary to press toward each other the apices 33 and 34 of the box at the junction of the edges 19, 20, 24 and 28 and at the junction of .the' edges 21, 22, 25 and 26, respectively, thereby to urge the sides of faces 12 and 13, respectively.

When the junction of the common sides of the faces 11, 15, 16 and 12, at the apex 31, and the junction of the common sides of the faces 13, 13, 17 and 14 at the apex 32 come together, as in the completely collapsed or flattened condition of the box 19, a flat structure a (Fig. 2) results that may be easily shipped, packaged. and stored.

It will be apparent that the flat structure 10a, from which the octahedral box 10 may be erected, has two superposed, substantially coextensive layers 35 and 36 (Fig. 2) each including a series of four triangular portions, for example, the portions 11a, a, 16a and 12a of layer 35, having successive common sides a, 23a and 22a, along which the triangular portions of each layer are hingedly or foldably connected. -All of such common sides of the triangular portions of each layer'converge to 4 and foldably or hingedly joined to, the side 37 of the triangular portion 11a, while the lower layer has a similar flap 40 extending along, and foldably or hingedly joined to, the side of the triangular portion thereof correspond ing to the side 33 of triangular portion 12a of the upper layer, that is, to the triangular portion of the lower layer corresponding to the face 13 of the erected box. As the flat structure 10a is being erected, in the manner described above, to form the octahedral box 10, the ends of the a single point, for example, the point 31a at which the common sides Zlla, 23a and 22;: all converge. Further, the edges of the two layers 35 and 36 are hingedly or foldably connected to each other only along the sides 19a, 24a, 26a and 21a of the triangular portions which are remote from the single point, for example, the point 31a, where the related common sides all converge.

In the flat structure 104; of Fig. 2, the parts thereof corresponding to parts of the octahedral box 10 are identified by the same reference numerals but with the letter a appended thereto. Thus, the triangular portions 11a, 15a, 16a and 12a of the layer 35 of the Hat structure, correspond to and form the faces 11, 15, 16 and 12 of the erected octahedral box 10, while the common sides 20a, 23a and 22a and the secured together edge portions 19a, 24a, 26a and 21a of the flat structure define the edges 20, 23, 22, 19, 24, 26 and 21 of the erected box. Although the lower layer 36 of the flat structure 10a is not wholly visible in Fig. 2, it is to be understood that the lower layer also has four successive triangular portions in the positions of, and underlying triangular portions 11a, 15a, 16a and 12a and correspond to and form the faces 14, 18, 17 and 13, respectively of the erected box 10, while the common sides of the successive underlying triangular pontions correspond to the edges 28, 27

and 25, respectively of the erected box. Further, the point 31a, at which common sides Zila, 23a and 22a of the triangular portions of layer 35 converge, corresponds to the apex 31 of the erected box 10, while the underlying point of the lower layer 36, at which the common sides of its triangular portions converge, corresponds to the apex 32 of the erected octahedral box;

Finally, it will be understood that the corners 33a and 34a of the flat structure 10a at the junction of the edge portions 1% and 24a and the common side 20a, and at the junction of the edge portions 21a and 26a and the common side 22a, respectively, correspond to the apices 33 and 34 of the erected octahedral box.

Thus, the flat structure 19a can be erected to form the box 10 merely by pressing the corners 33a and 34a generally toward each other. Since the sides 37 and 38 of the triangular portions 11a and 12a, respectively, of the upper layer 35 are free of the corresponding sides of the underlying triangular portions of lower layer 36, the pressing towardeach other of corners 33a and 34a results in the movement of point 31a of layer 35 away from the corresponding underlying point of layer 36 while thetriangular portions of each layer are progres sively angularly displaced relative to the contiguous triangular portions with which they have contiguous sides, as in Fig. 3, until, finally, such triangular portions of the fiat structure being erected occupy the positions of the corresponding triangular plane faces of the octahedral box 10.

In order to close the box it across the two contiguous edges 29 and 30 lying in the same plane, the layer 35 of the fiat structure ltla has a flap 39 extending along,

flaps 39 and 40 adjacent the developing apices 31 and 32, respectively, are tucked inside the faces 12 and 14, respectively, as shown in Fig. 3, so that, in the fully erected condition (Figs. 4 and 6) flap 39 extends across edge 29 and under face 12, while flap 40 extends across edge 39 and under face 14, thereby to close the edges 29 and 30.

It will be apparent that, when the box is in a partially erected condition, for example, as in Fig. 3, the free sides of the triangular faces 11, 12, 13 and 14 define an opening through which articles can be inserted or removed, and that, as the box is manipulated to its fully erected condition, the size of said opening is progressively decreased until the latter is fully closed in the fully erected condition.

In order to provide a simple means for releasably securing the box 10 in its fully erected or closed condition, the ends of the flaps 39 and 40 which are adjacent to each other in the fully erected condition are formed to then interlock slightly, as shown particularly in Fig. 12. Since the sheet material of which the box 10 is formed, for example, cardboard, stiff paper and the like, has considerable resiliency, the slight interlock of the flaps 39 and 40 can be easily disengaged in response to the pressing toward each other of the apices 31 and 32 when it is desired to open or collapse the box 10. As seen in Fig. 2, the ends of the flaps 39 and 40 are generally cutback at an angle to avoid substantially interference be-' tween the ends of the flaps and the adjacent faces of the box 10 during the erection of the latter. However, in order to provide the desired slight interlock of the adjacent ends of flaps 39 and 40 in the fully erected or closed condition of the octahedral box; the ends of the flaps, which are adjacent to each other in the erected or closed condition, have relatively short edge portions 41 and 42, respectively, which are longitudinally aligned with the adjacent edge portions 19:: and 21a in the flat condition of the box structure (Fig. 2). Since the flaps 39 and 40 are angularly disposed with respect to the related faces 11 and 13 by engagement. under the faces 12 and 14, respectively, in the fully erected or closed condition of the box, the short end edges 41 and 42 of the flaps 39 and 40, respectively, incline ,towardeach other and overlap, asshown in Fig. 12, to provide the desired intererection of the box from its flat condition, as shown in Fig. 3, the flaps can twist about their longitudinal axes when the edge portions 41 and 42 first engage, thereby to permit passage by each other of such overlapping edge portions. Only when the box 10 is in its fully closed or erected condition, do the faces 12 and 14 engage the flaps '39 and 40 at the overlapping ends thereof to ensure the interlock of edge portions 41 and 42. I

In accordance with the present invention, the flat structure 10a, and hence the box It erected therefrom, is

formed from a one-pieceblank of suitably folded and glued cardboard, stiff paper or other sheet material. In Fig. 1, a blank configuration is illustrated which is best adapted for the economical utilization of the sheet material from which the blank is to be cut. Thus, it will be seen that successive identical blanks 10b, and ltlb may be cut from a web or strip S of suitable sheet material with a minimum waste of the latter. In the blanks of Fig. 1, the several parts, or portions and foldlines thereof are identified by the same reference numerals'employed in connection with the corresponding parts and edges, respectively, of the previously described box 10, but with the letter b appended thereto.

It will be seen that each of the blanks b and 10b: includes eight triangular portions 11b, 12b, 13b, 14b, 15b, 16b, 17b and 18b, which are arranged in two groups A and B of equal number, the four triangular portions of each group having successive common sides all converging to a single point, and one triangular portion of one of said groups having a single common side with one triangular portion of the other of said groups. Thus, in each of the blanks of Fig. 1, the triangular portions 13b, 12b, 16b and 17b, corresponding to the faces 13, 12, 16 and 17 of box 10, form the group A and have successive common sides 21b, 22b and 26b along which the blank is scored to define fold lines corresponding to the edges 21, 22 and 26 of the box 10, while the triangular portions 18b, 14b, 11b and 15b, corresponding to the faces 18, 14, 11 and 15 of box 10, form the group B and have successive common sides 28b, 19b and 20b along which the blank is scored to define fold lines corresponding to the edges 28, '19 and 29 of box 10. The common sides 21b, 22b and 26b of the triangular portions of group A converge to a single point 34b corresponding to the apex 34 of the erected box, while the common sides 28b, 19b and 20b of the triangular portions of group B converge to a singlepoint 33b corresponding to the apex 33 of the erected box. Finally, it will be seen that only the triangular portion 17b of group A has a single common side 27b with only the triangular portion 18b of group B.

' The sides of the triangular portions 11b and 13b remotefrom the points 33band 34b, respectively, have flap defining portions 39b and 40b, respectively, extending therealong and corresponding to the flaps 3 9 and 40 of box 10, the flap defining. portions 39b and 40b being joined .to the related triangular portions 11b and 13b at scored fold lines 43 and 44, respectively. Further, although the end edges of the flap-defining portions 39b and 40b generally converge toward each other in the directions away from the related fold lines 43 and 44, the end of flap defining portion 3% adjacent fold line 1% has an edge portion 41b which is longitudinally aligned with the latter and, similarly, the end of flap defining portion 40b adjacent fold line 21b has an edge portion 42b which is longitudinally aligned with the latter, so that the edge portions 41b and 42b of the blank correspond to the interlocking edge portions 41 and 42 of the flaps on box 10. Finally, each of the blanks ltib and 1%,, of Fig. 1 has flaps 45, 46 and 47 extending along the outer or free sides of, triangular portions 13b, 16b and 18b and joined to the latter along scored fold or hinge lines 48, 49 and 50, respectively. I I

In order to form the ,flatstructure 10a of Fig. 2 from one of the one-piece blanks 10b or 10bof Fig. 1, adhesive is applied to the top surface, as viewed in Fig. 1, of each' of thefiaps 45, 46 arid 47 of the blank. Then, assuming thatthe blank faces as shown in Fig. 1, triangular portion underlie tr-iangular portion 12b; flap 47 is turned under adjacent triangular portion 18b; triangular portions 13b, 12b and 16b are folded, as a unit, about fold line 26b so that portion 16 underlies portion 17 and so that flap 45 extends under the adjacent edge portion of triangular portion 17 to adhesively secure the latter to triangular V portion 13; and, finally, the triangular portions 11 and 15 are folded under, as a unit, about the fold line 19b to respectively underlie the triangular portions 14b and 18b with the free edge portions of triangular portion 15b being applied against the adhesive coated flaps 46 and 47 and thereby secured to the triangular portions 16b and 18b. I I When the above described folding operations are'completed, a flat structure 10a will result'with the layer 36 on top and the flaps 39 and 40 at the lower edge.

13b is folded about fold line 21b to flat structure can be merely turned over to dispose it in the position corresponding to that shown in Fig. 2, or the flat blank can be reversed before commencing the folding thereof. I

Although the configuration of the blanks shown in Fig. 1 permits close nestin'gthercof on the web .or'strip S of sheet material so that there is substantiallyrno waste of the latter, it may be desirable to sacrifice this economy,

to a limited extent, in order to facilitate the foldingof the blanks in existing machines adapted for that'purpose. Thus, in Fig. 7, two blanks 10, and 100, are shown as they are cut from a strip or web S of suitable sheet material. In the blanks of Fig. 7, the several parts and fold lines thereof are referred to by the same reference numerals employed in connection with the corresponding parts and edges'of the octahedral box 10 of Fig. l, but with the letter 1: appended thereto. As in the case of the blanks 10b; and "10b; of Fig. 1, the blanks of Fig. 7 for formingoctahedral boxes of the kind describedin connection with Fig. 1 each include eight triangular portions 110, 12c, 13c, 14c, 15c, 16c, 17c and 180 which are arranged in two groups A and B of equal number, the four triangular portions of each group having sucessive common sides all converging to a single point, and one triangular portion of one of the groups having a single common side with one triangular portion of the other of the groups. However, in each of the blanks of Fig. 7, in order to facilitate the subsequent folding and gluing thereof, the twogroups A and B are arranged to provide symmetry, that is, the points at which the common sides of the triangular portions of the respective groups converge are disposed at thesameside of the blank. Thus,'in the blank 10c group-A consists of triangular portions 160, 12c, 13c and 17c arranged successively with their common sides 22c, 21c and 25a converging'to a single point 34c, while group B consists of triangular portions 180, 14c, 11c and 15c arranged successively with their common sides 28c, 19c and 200 converging to a single point 330 which is at the same side of the blank as the point 340, and the one triangular portion 170 of group A has one common side 270 with the one triangular portion 18c of group B. Further, the blank 10c has flap defining portions 39c and 400 extending along the sides of triangular portions 11c and 130 remote from points 33c and 340, respectively, and joined to. the related triangular portions along fold lines 430 and 440. The blank 100 also includes flap defining portions 45c, 46c and 470 extending along, and foldably joined to, the side of triangular portion 160 remote from point 34c and the free sides of triangular portions 17c and 18c, respectively. j

. In folding and gluing the blanks of Fig. 7 in order to provide the flat structure 10a of Fig. 2, and assuming that each blank is initially disposed as in Fig. 7, the flap defining portions 46c-and 47c are folded upwardly to overlie the adjacent side portions of triangular portions 170 and 180, and adhesive is applied to the surfaces of the flap defining portions which face upwardlyfollowing the above folding operation. Then triangular portions 16c and'12c are folded upwardly as, a unit about the fold line 21c so that portion 16c overlies portion. 170

and portion12c overlies portion 13c with the flap defining portion 450 extending'onto portion 18c and adhesive is applied to the surface of portion 450 which.

faces upwardly, and, finally, thetriangular portions 15:: and are also folded upwardly as a unit about the fold line 190 so that portion overlies portion and portion 11c overlies portion 14c. At the conclusion of the above simple and symmetrical folding operations which can be easily effected in existing machines adapted for that purpose, flap 450 will secure portion 150 to spectivel-y. 75

T-he several triangular portions of the blanks Figs.

1 and], respectively, and of the flat structure of Fig. 2, and the faces of the octahedral box 10 of Figs. 4, 5 and 6, are all identical equilateral triangles, so that the box 10, in its fully closed or erected condition, has the configuration of a regular octahedron. However, the present invention is not limited to that configuration, in that the several triangular portions of the blank and flat structure formed therefrom and the corresponding triangular faces of the octahedral box may be merely identical or equal isosceles triangles where the sides of equal length enclose an angle, that is, the angle at the apex of the triangle, which is less than 90 degrees. Thus, each triangular portion of the blank or flat structure and each corresponding triangular face of the box may be an isosceles triangle having an apex angle of less than 60 degrees or of more than 60 degrees but, in any case, substantially less than 90 degrees.

For example, referring to Fig. 8 of the drawings, it will be seen that a blank 10d embodying the present invention may include triangular portions 11d, 12d, 13d, 14d, 15d, 16d, 17d and 18d, and flap defining portions 39d, 40d, d, 46d and 47d all arranged in the same relationship as the correspondingly numbered parts of the blanks of Fig. 7, but with the several triangular portions of the blank being equal .or identical isosceles triangles each having an apex angle a which is substantially less than degrees so that, when the blank 10d is folded and glued in the manner described with reference to Fig. 7 to provide a flat structure generally of the kind illustrated in Fig. 2, and that flat structure is then erected, the resulting octahedral box lfle (Fig. 9) will have isosceles triangular faces, for example, the faces 13c and 17a visible in Fig. 9, which each have a height or perpendicular distance from the vertex to the base substantially greater than the length of the base, thereby to provide an octahedral box which is generally elongated in the direction of its axis passing through the apices defined by the vertices of the triangular faces.

0n the other hand, as shown in Fig. 10, a blank 10) for producing an octahedral box in accordance with the present invention may have triangular portions 117, 12f, 13 14], 15 16f, 17f and 18) and flap defining portions 397, 40f,.45 46] and 47f arranged in same relationship as the blanks of Figs. 7 and 8, respectively, but with the several triangular portions being identical isosceles triangles each having an angle ,b at its apex which is larger than'tiO degrees. and substantially smaller than 90 degrees so that the resulting octahedral box 10g (Fig. 11) will have isosceles triangular faces, for example, the faces 3 and 17g visible in Fig. 11., which each have a height or perpendicular distance from its apex or vertex to its base substantially smaller than the length of the base, and the resulting box will be of generally squat appearance.

It will be apparent that the alternative blanks shown in Figs. 8 and 10, respectively, when folded and glued in the manner recited in connection with the blanks of Fig. 7, will produce flat structures similar to that illustrated Fig. 2, with the exception that the triangular portions of the flat structure, rather than being equilateral, as in Fig. 2, will be isosceles triangles having apex or vertex angles which are either smaller or larger, asthe case may be, than the angle of 60 degrees.

it is apparent that boxes embodying the present invention may be employed as containers or receptacles for a wide variety of articles to provide a novel package by reason of the unique shape thereof and the ease with which the boxes can be either flattened for convenient storage and shipment or erected for the reception of articles. Further, when the faces of boxes embodying this invention are'suitably decorated, such boxes provide attractive decorative objects useful, for example, as Christmas tree ornaments and the like, which have the advantages, over conventional fragile glass ornaments, of being unbreakable and collapsible for easy storage, shipment and merchandizing. Further, since boxes embodying the present invention and usable as Christmas tree ornaments and the like, are formed from one-piece blanks cut from flat sheet material, such as, cardboard and the like, such fiat blanks may be easily decorated by a conventional printing operation, thereby to permit the relatively inexpensive production of intricate, multi-color CESSlgD-S.

Although the use of the described box-like structures as decorative ornaments for Christmas trees and the like has been mentioned above, it is apparent that the boxlike structures embodying this invention may have many other uses, such as, for example,.as display pieces, shipping containers or cartons, or, when suitably dimensioned and formed of translucent plastic material, as lampshades.

Although illustrative embodiments of the present invention have been described in detail herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications may be eflected therein, by one skilled in the art, without departing from the scope or spirit of the invention, except as defined in the appended claims.

What is claimed is:

l. A one-piece flat cardboard blank for forming an octahedral box of the described character, comprising only eight triangular portions arranged in two groups of equal number, the triangular portions of each group having successive common sides along which said triangular-portions are foldably connected with said successive common sides all converging to a single point, and only one of said triangular portions of one of said groups having the side thereof which is remote from the related single point in common with, and foldably connected to, the side of only one triangular portion of the other of said groups which is remote from said single point of said other group, said triangular portions of the respective groups having a common side being at the ends of their related groups.

2. A one-piece flat cardboard blank as in claim 1; wherein said single point at which the common sides of the triangular portions of said one group converge and said single point at which the common sides of the triangular portions of said other group converge are at opposite side edges of the blank.

3. A onepicce flat cardboard blank as in claim 1; wherein said single point at which the common sides of the triangular portions of said one group converge and said single point at which the common sides of the triangular portions of said other group converge are at the same side of the blank. l

4. A one-piece flat cardboard blank as in claim 1;

' wherein each of said triangular portions has at least two sides of equal length enclosing an angle of less than ninety degrees. a

5. A one-piece flat cardboard blank as in claim 1; wherein each of said triangular portions is of equilateral configuration.

References. Cited in the file of this patent UNlTED STATES PATENTS 7 403,993 Great Britain Jan. 2, 

